Furnace conveyor roll



Dec. 4, 1956 N. B. oRNlTz` 2,772,372

FURNACE CVONVEYOR ROLL Original Filed March ll. 1950 INVENTO`R NATHANIEL B. ORNrr 65 d-wfw United States PatentO FURNACE CONVEYOR ROLL Nathaniel B. Ornitz, Pittsburgh, Pa., assignor to Blaw- Knox Company, Pittsburgh, Pa., a corporation of Delaware Original application March 11, 1950, Serial No. 149,079,

now Patent No. 2,603,578, dated July 15, 1952. Divided and this application December 19, 1951, Serial No. 262,413

, 7 Claims. (01.26346) This invention relates ,tofurnace conveyor rolls. It

has to do particularly, although not exclusively, with furnace conevyor rolls around which metal; strip is passed and advanced through continuous heating furnaces to be heated therein. A purpose of the inventionV is to provide furnace conveyor rolls which remain smooth in continued use andv have no deleterious effect upon the work carried therebyi'n the presence'of the furnace atmosphere at No. 2,603,578, which in turn is in parta continuation of my application Serial No. 74,451, tiled February 3, 1949, now abandoned.

For purposes of explanation and illustration the invenl tion will be described as embodied in a furnace conveyor roll for passing strip through an annealing furnace.

Those skilled inthe art are aware of the difficulties encountered in the use of metallic conveyor elements in influenced by the `tension'of the strip passing around-the rolls, the compositionof the strip carried by the rolls and the composition and temperature of the furnace atmos- Patented Dec. 4, 1956 f" A 1 ce number of respects. My conveyor roll has improved accretion inhibiting properties relatively to not only silicon carbide inserts as disclosed in Patent No. 1,951,766, but also the oxide coated conveyor elements disclosed in said applications. Also my improved conveyor roll has materially increased strength for the quantity of costly high temperature alloy used in its manufacture.

My improved furnace conveyor roll has a carbonaceous workengaging portion. The work-engaging portion of the element may comprise graphite particles bonded together. I vpreferably employ a baked mass of graphite particles and a binder whichimay be a bituminous binder such as tar bindingthe particles together. The body of the roll is preferablyof metal, a high temperature alloy of known composition desirably being employed.

My improved furnace conveyor roll may comprisea metal body with a carbonaceous sleeve .fitted thereon.

The metal roll body may be` a hollow alloy metal body, e

mass of baked graphite particles and a binder tightly embracing the body. y

Other details, objects and advantages of the invention v will become apparent as the following description of a present( preferred embodiment thereof proceeds.

In the accompanying drawings I have shown a present preferred embodiment of the invention in which Figure 1 is a diagrammatic view of a heat `treating chamber showing how strip may bevsupported on my furnace conveyor rolls for passage therethrough;

cross section of Va furnaceconveyor roll; and

Figure 3gis` Van end view of the furnace conveyor roll shown in n,Figurey l. l

Figure 1 shows a furnace'chamber designated generally by reference numeral 20 through which strip 21 is adapted to be drawn, the stripfpassingover a series of rolls 'at n phenomenon of accretion formation is complex land vis J pher'e as well as the character of the roll surface. l 4The problem is similar to the'handling of sheets in annealing furnaces on carriers or roller tables which is discussed,

' the refractory inserts supporting the work passing through the furnace. While no oxideY coating forms on silicon carbide inserts and suchrollsare satisfactory'f'or anneal` ing sheets,v vit has been lfound that in"continuous strip l steel-strip, some accretionsform on silicfon .carbide inserts,l

i Furthermore, thejprovision 'and vapplication" of the gre?V prilsing metal -bodieshaving oxidefcoati'ngsov the work#A carrying' 4ortions "thereof, which` oxide coatings inhibit,

the',f ori'natipn'Jl of accretionsi on the conveyor elements".` While the conveyor elements "of those Y applications' have prdvd'fsa isfactoryg-especially in highly oxidizing,4 atmospheres or Ythelowerranges `of-s'triptension, rI* have de vised a conveyor-frll which is"superior theretof'in a annealing furnaces wherethe strip wraps Varoundthe rolls under tension', Vand- ,especially in annealing high .silicon Y ythe/top of the furnace andlbeneath a series of rolls at the bottom of the furnace,all of the rolls desirably being Vof uniform construction and each being'designated by reference numeral `22,'the structures of the rolls being shown in Figures 2 and 3. The rolls 22 maybe driven or may turn idly `as the strip is drawn through the'chamber. The chamberis heated Vinternally by suitable heating meanssuch'as electric heating elements (not shown).

Referring now more particularly to FigurestZ and 3, theY furnace conveyor roll shown therein comprises a metal Vbodydesignated generallyby reference numeral 2 and a l graphiteL'sleeve'l The roljljbody comprises a barrel 4, two shaft ends l5', Vtwofdrive rings. 6 and two closure plates 7, the shaft ends` S, beinguiilled heatinsulating material,fl`he barrelv4, Vtherfsh'aft endsS, thezdrive rings;V and the closure p1ates7 may, be of any suitable 'ferrous' or non-ferrous high temperaturealloy such as is iised inthemanufacture of furnace conveyor elements.v

'The-barrel .-l'has .'axially spaced circumferential proline jections or lands 49 forming bearings for the sleeve Sande Y afi/:ent 19 establishingcommunicationbetween the outisi'deiandthe insidefof the barrel 4to permit venting of if heated air fromwithin 'thebarrel when the roll is brought' up to teniperaturefand entrance int-o `the barrelof air nions'f14 o'fzrelatively"great and relatively small diam Figure 2 'is a view partly in elevation and partly in axial e graphite.

eter, The roll may be mounted for rotation in conventional manner.

The ends of the barrel 4 are welded to the shaft ends 5 by welds 15. The closure plates 7 are weldedV to the shaft ends 5 by welds 1'6. The drive rings- 6- are Awelded to the barrel' 4 by welds 17, but one of the drive rings is not applied and welded to the barrel until after the sleeve 3' has been putin place on the barrel. Each of the drive rings 6 has a series of circumferentially spaced radially and axially extending projections 18 eachV of which enters' a slot 19' provided therefor in one of the ends of the sleeve 3 thus 'locking the sleeve to the roll body so'v that the r'oll. functions asa unit. As clearly showninthe drawings, each of the drive rings 6 interts with `they sleeve 3` and bears against the sleeve circumferentiall'y and'axially only' to hold the Vsleeve against Vturning relatively tothe rollbody 2. i Y

The sleeve 3 constitutes the work-engagingrportion of the roll' and itsv outer cylindrical surface is the workengaging surface of the roll.

Preferably finely vdivided particles of graphite are 'bonded with a suitable binder, such, for example, as bituminous material such a's tar,4 compressed into hollow cylindrical shape as Shown and baked.V The 'slots 19 may be molded into the sleeve at the time of its formation or may becut out afterward. Y'

The sleeve' 3 may, if desired, be of amorphous carbon instead of graphite. A sleeve 0f amorphous carbon may be made by baking in a kiln a mixture of anthracite coal, petroleum coke and pitch. An amorphous carbon sleeve may be changed into graphite by being further heated in a graphit'izing furnace to eect transition of the carbon to graphite form. i

When the parts are cold the outside diameter of the circumferential projections 9' is slightly less than the inside diameter of the sleeve 3 so that the sleeve may easily be applied over the barrel. However, when the roll is brought Vup lto temperature expansion of the barrel results in a tight fit betweenthe barrel and the sleeve so that the'A sleeve 'tightly embraces* theV rollbody. Thisis' a feature of consequence of .my improvedroll. At Vhigh annealing temperatures, such as the temperatures at Vwhich silicon steel sheets are annealed, graphite is mechanically stronger than any known high temperature alloy and a Y sleeve lsuch'as 'the sleeve 3 contributes I'materially totl-'ie stiffness and strength -of thewroll.` Assuming` algiven desired'` outside diameter-of the. roll. and comparing the graphite roll shown in the. drawingslwiththe voxid'ejco'atedf Y' Y' rolls of the applicationsi above referred to, whileiin the oxide coated roll's the metal roll body has lalmrostthe fu'll roll' diameter and'has the largest section modulus vpossible, which permits use of a relatively thin wall in 'the metal roll'bo'dy, in 'the roll'shown in theydrawings, al-

. though the. section modulus gof the metal body is much lower, this is more than compensated for -by the reinforcing effectof the graphite shell' or sleeve whichlmakes ,possible the use of a very thin walledA .body barrel. `AsY stated above, whengthe froll'is brought up'to .the

temperature' at which it is'usedjin Vsupporting and advancingfworl; througha heatingfurn'ace the metal-roll Ybody e Y expandsand forms-a tight fit withi the'insidei'of the' s'le'eve 3, whereby thereinforcing:etfectfof'the sleevefis produced.

v i In addition to' the mechanicalfadvantageof t-he'struc- ,ture just explainedrit. is found] that the lgraphite workengaging surface is superiortopsilcn carbide and also' havior of other rolls suggested and used. lt is, 0f course, 'understood that the furnace atmosphere in which my roll is used should not be excessively oxidizing in character, so as to rapidly consu-me the graphite shell; but slow oxidation merely gra-dually reduces the roll diameter, without other harmful effect' and does not detract from the advantages which the use of graphite shell provides.

While I have shown and described a present preferred embodiment of the invention it is tov be distinctlyV understood that the invention is not lmited thereto but may be otherwise variously embodied within the scope of the following claims.

y vI claim: l' Y l. A furnace conveyor roll comprising a body of structural material, a work-engaging sleeve of material different' from the material ofthebodyj disposed `about and immediately adjacentv a portion of` the body and abut nient means carried by the body engaging the end portion'ofthe sleeve to maintain the sleeve in position axially ofthe body',` the'- centralportion of vthesleeve. being slightly spaced' from the body at room temperature but through expansion engaging the body aty working temperature. A y u i 21A furnace conveyor roll comprising `abody of material having a relatively great coeflicient ofexpansion and a work-engaging sleeve of material having a relatively smalli coefficient of 'expansion disposed about a portionjof the body, the outside dimension ofthe body being less than the` inside dimension of the sleeve at normal atmospheric temperatures to provide clearance between the body and sleeve to facilitate application of the sleeve about the body but thediffference between said dimension being limited so that when the roll is heated to a temperature materially higher than normal atmospheric temperatures for heat treating work supported byv the roll the body expands relatively to the sleeve into tight fitting engagement with the sleeve.

- 3. A furnace conveyor roll' comprising a body of generally cylindrical shape having annular outward' projections spaced apartaxiallyfof thebody and a workengaging carbonaceous sleeve disposed' about the body and bearing against saidproje'ctions. e i l Y Y 4. "A furnace conveyor rollV comprising a body of Vmaterial having a-'relatively greatfc'oefcientof expansion, the` bodyw being of generally cylindrical' shape and having annular outward proi'ections spaceda'part axially vof the body,V and a work-engaging 'sleeve of material having av relatively small coefficient'of*expansion disposed` about the'body and about' saidv projections, thcfoutside'rdimension'vof 'ther body at said proiect'ions being lessthan the inside dimensionof thev sleeve at' no'r-mqal'atmosphcric temperatures t'opr'ovide' clearai-icev between the body and Sleeve to facilitate application ofthe sleeve about the body Y but the difference between. said dimensions being limited treatingwork supportedV by the iroll the body expands 'i relativelyto'the sleeve `bringing saidprojections into tight' Y fitting 'engagement with the sleeve.

5.' A furnace'conveyor roll-lcomprising a" metal body ofgenerall'y cylindrical' shapefhaving annular outward projectiotisf'spaced apart axially," the body. aiidfa car` -bonaceous' workengaging sleeve "disposed about' the' body.

and about said projections, thefioutside dimension ofthe body rat said` projectionsl'being less'` than the inside Vdimension. joffy the'4 sleeve at normal. atmospleric-temperatures tol provide clearance between thefbodyaand sleeve to facilitate.: application of .the sleeve about, the 'body but the dilerencetbetween saidlimensions 'beingilimited so that whenthe'rollis 'heated to a temperature materially higher than:norma'l. artnio'sphericI temperatures 'fori heat,V treating work 'supported 'bytheV rollt-he body expands relatively' to the sleeve bringing .f said; projections into 'fright[fitting-l tinuous from end to end of the roll and having trunnions at its ends for rotatably supporting ythe roll, the body having a generally cylindrical central portion, a workengaging sleeve disposed about and mounted directly upon the generally cylindrical central portion of the body and abutment portions carried by the body engaging the sleeve at the respective ends thereof and fastened to the bodyto maintain the sleeve in position axially of the body, at least one of said abutment portions intertting with the sleeve and bearing against the sleeve circum- 10 4ferentially and axially onlyr to hold the sleeve against turning relatively to the body. r

7. A furnace conveyor roll comprising a body continuous from end to end ofi-the rolland having trunnions at its ends for rotatably supporting `the roll, the Ibody having a.v generally cylindrical centralg portion, a workengaging sleeve disposed about the generally ycylindrical central portion of the body, the work-engaging sleeve having at an end thereof a radial slot entering axially into the sleeve from the end of the sleeve, and abutment portions carried by the body engaging the sleeve at the respective ends thereof and fastened to the body to main tain the sleeve in position axially of the body, the abut` ment portion at the first mentioned end of the sleeve having means entering the slot to hold the sleeve against turning relatively to the body.

References Cited in the le of this patent UNITED STATES PATENTS 669,765 Reichhelm M-ar. 12, 1901 1,657,212 Hitchcock Ian. 24, 1,92- 8 1,783,465 Fox Dec. 2, 1930 1,923,772 Carpenter Aug. 22, 1.933 1,998,627 Kormann Apr. 23, 1935 2,156,395 Klouma-n May 2, 1935 2,020,219 Sirianni Nov. 5, 1935 2,263,439 Hansen Nov. 18, 1941 2,428,344 Stookey Sept. 30, 1947 

